The present invention relates to a method and a device for recycling coated glass, especially glass of cathode-ray tubes.
Coated glass is used in a plurality of applications in various technological fields. For example, cathode ray tubes for television sets, computers, radar screens etc. are comprised of a glass screen with a coating of a fluorescent substance and a glass cone which is coated with a conductive lacquer. As a protection against radiation the screen glass contains barium and the cone glass contains lead oxide and barium in smaller concentrations.
Discarded cathode-ray tubes are disposed of in landfills despite the fact that the coatings contain not especially bonded poisonous substances. Cathode-ray tubes rejected during manufacturing because of defects that cannot be corrected are also disposed of in landfills.
In addition to the present environmental hazard due to the release of poisonous materials, the disposal of the cathode-ray tubes having a relatively large volume result in a considerable landfill space being used up and to the loss of glass (up to 20 kilograms per tube). In the Federal Republic of Germany approximately 4,000,000 cathode ray tubes as well as 1,000,000 tubes of computer monitors are discarded annually and, in addition, approximately 100,000 tubes are rejected during manufacturing so that a considerable amount of landfill space is needed for their disposal.
From German Offenlegungschrift 39 01 842 a method for separating screen glass and cone glass of a cathode-ray tube is known. The cone and the screen, after their separation, may be cleaned, for example, by sand blasting or cleaning with high pressure water jets and can then be recycled. With this method the landfills are relieved to some extent. However, such a method is very energy-intensive and only successful when the glass screen, respectively, the glass cone are not damaged due to the sand blasting or high-pressure water jet treatment to such an extent that a reuse is impossible.
It is therefore an object of the present invention to provide a method for recycling of coated glass with which especially cathode-ray tubes may be recycled.